Optical Enhancement of Fluorine‐Doped Tin Oxide Thin Films using Infrared Picosecond Direct Laser Interference Patterning

Abstract

Surface texturization of Transparent Conductive Oxides (TCOs) is a well‐known strategy to enhance the light‐trapping capabilities of thin‐film solar cells and thus, to increase their power conversion efficiency. Herein, the surface modification of fluorine‐doped tin oxide (FTO) using picosecond infrared direct laser interference patterning (DLIP) is presented. The surface characterization exhibits periodic microchannels, which act as diffraction gratings yielding an increase in the average diffuse transmittance up to 870% in the spectral range of 400–1000 nm. Despite the one dimensionality of the microstructures, the films did not acquire a significant anisotropic electrical behavior, but a partial deterioration of their conductivity is observed as a result of the removal of conductive material. This work proposes the feasibility of trading off a portion of the electrical conductivity to obtain a substantial improvement in the optical performance.

Effects of sub-picosecond direct laser interference patterning on the optoelectronic properties of fluorine-doped tin oxide thin films

“…[12][13][14][15][16][17] To approach the maximum theoretical efficiency of solar cells, 18 different strategies involving surface modification strategies of FTO thin films have been studied. In this direction, previous works have sought to increase the total transmittance (T tot ), 19 to enhance the optical path by scattering the incident light (T diff ), 20 or to reduce the sheet resistance through the modification of the FTO microstructure by laser ablation, 21 laser annealing, 22 or by changing the fluorine doping concentration. 23 In regards to surface modification using laser radiation, Li et al achieved an increase in the crystallite sizes of SnO 2 particles of B75% by annealing FTO thin films with a 532 nm nanosecond pulsed laser.…”

“…[36][37][38] To the best of our knowledge, only a few studies were published in which DLIP was employed to modify the optoelectronic characteristics of TCOs using stable and costeffective IR laser sources. 20,39 For instance, Zhang et al structured FTO thin films with a 1030 nm femtosecond laser, obtaining birefringence properties. The fabrication of nanogrooves with a spatial period of B300 nm was achieved and the birefringence (Dn) reached a value of 0.20.…”

Customizable-Width Conducting Polymer Micro/Nanoarrays by Subpicosecond Laser Interference Patterning

“…A total of 10 measurements were taken for each sample, 5 repetitions for longitudinal mode and 5 for transversal mode for statistical reasons. The used current was fixed to 1 μA, and a correction factor of 0.75 was applied for compensating the limitation of the current path provoked by the proximity of boundaries . The sheet resistance ( R S ) was obtained by using the formula R S = R × 4.5 × 0.75.…”

“…The utilized DLIP processing approach has been previously reported in more detail elsewhere. 27 The PANI@PMMA samples' surfaces were analyzed using a high-resolution scanning electron microscope (SEM) (Quattro ESEM, Thermo Fischer Scientific, Germany) at an accelerating voltage of 5 kV.…”

“…The used current was fixed to 1 μA, and a correction factor of 0.75 was applied for compensating the limitation of the current path provoked by the proximity of boundaries. 27 The sheet resistance (R S ) was obtained by using the formula R S = R × 4.5 × 0.75. The sheet resistance of the pristine (nonlaser processed) films was found to be R SP = 27 ± 4 kΩ sq −1 .…”